cvirgil467
Senior Member
- Location
- NewYork
I am getting stumped on an item for a fire pump:
Stump #1 - the 15% voltage drop requirement. That's easy to calculate from the NEC table for locked rotor current. My question is, how would the starting kVA required to start the fire pump at the minimum 15% voltage drop be calculated. If i saie for a 15% voltage drop then i would need to know the locked rotor current at 15% voltage decrease.
15% voltage drop @ 480v = 408v
Wouldn't i need to know the locked rotor current for 408v to find the starting kVA allowing a 15% voltage drop?
What is also confusing is the generator manufacturers list starting kVA at 30% voltage dip which exceeds NEC voltage drop limits for fire pumps.
Anyone have any example?
Thanks.
c
Stump #1 - the 15% voltage drop requirement. That's easy to calculate from the NEC table for locked rotor current. My question is, how would the starting kVA required to start the fire pump at the minimum 15% voltage drop be calculated. If i saie for a 15% voltage drop then i would need to know the locked rotor current at 15% voltage decrease.
15% voltage drop @ 480v = 408v
Wouldn't i need to know the locked rotor current for 408v to find the starting kVA allowing a 15% voltage drop?
What is also confusing is the generator manufacturers list starting kVA at 30% voltage dip which exceeds NEC voltage drop limits for fire pumps.
Anyone have any example?
Thanks.
c